1. Field of the Invention
This invention relates to a color filter grade photosensitive resin coloring composition comprising a resin and a dye and serving as a material for forming a colored layer in a color filter and a color filter using the composition. More particularly, it relates to a color filter grade photosensitive resin coloring composition obtained by using as a dye any member selected from the class consisting of a (C) group alone, a combination of (A)+(B) groups, a combination of (A)+(C) groups, a combination of (B)+(C) groups, and a combination of (A)+(B)+(C) groups, providing (A) is a group of quinizarine compounds having absorption in a visible radiation range of 480-700 nm, (B) is a group of anthraquinone compounds having absorption in a visible radiation range of 400-650 nm, and (C) is a group of phthalocyanine compounds having absorption in a visible radiation range of 600-700 nm and a color filter using the composition.
Further, since the color filter grade photosensitive resin coloring compositions of this invention have absorptions in a visible radiation range of 400-700 nm and excel in solubility in resins and these dye compositions also exhibit excellent lightfastness and thermal resistance, they manifest an excellent effect as display materials possessing absorptions in a visible radiation range in the field of photoelectronics information when they are used in color separation filters for camera tubes, color filters for liquid crystal displays, optical color filters, and color filters for plasma displays, for example. This invention manifests an exceptionally outstanding effect when it is used in color filters for liquid crystal displays of the three primary color type.
This invention also relates to a method for the production of a color filter, resorting to a simple procedure comprising the steps of forming colored layers for the formation of color patterns by the use of the color filter grade photosensitive resin coloring compositions mentioned above and patterning the colored layers by the photolithographic technique thereby forming a plurality of color patterns successively on one surface of a substrate without requiring a treatment for preventing mixture of colors and thereby accomplishing the production by a simplified process.
This invention further relates to a particularly novel anthraquinone compound among other anthraquinone compounds of the category (B) mentioned above, a method for the production thereof, and an electrophotographic color toner composition, a thermosensitive sublimation transferring sheet, an ink jet grade ink composition, and a color filter which severally contain the anthraquinone compound.
The novel anthraquinone compounds of this invention possess absorptions in the yellow-red-blue region of 400-650 nm, excels in solubility in solvents and resins, and also excels in lightfastness and thermal resistance and, therefore, manifests an excellent effect as displaying material or recording materials possessing absorptions in a visible radiation range in the field of photoelectronics information when they are used in sublimation transfer grade dyes, ink jet grade inks, color separation filters for camera tubes, liquid crystal display grade color filters, optical color filters, color toners, bar code grade inks for preventing attempts to raise or counterfeit prints, guest-host type liquid crystal display grade dichromatic dyes, deflecting plate grade dichromatic dyes, optical recording materials adapted for compact discs, and the like. They manifest the excellent effect particularly when they are used as yellow type coloring agents.
Further, the novel anthraquinone compounds of this invention manifests an excellent effect as quality coloring agents excelling in solubility, exhibiting high fastness, and absorbing visible radiations in the yellow-red-blue region when they are used in dyes for fibers, coating materials for automobiles, coating materials for buildings, coloring agents for printing plates, inks for writing utensils, coloring agents for glass flakes, coloring agents for eyeglasses, and the like.
2. Description of the Prior Art
In recent years, the liquid crystal display devices (LCD) have been finding rapidly growing utility in display devices for personal computers, word processors, car navigators, and portable telephones and have been enlarging markets for these products as levered by the advantages of successful adaptation thereof for all-color operations and reduction of prices thereof. The color filters are indispensable to the adaptation of such displays for all-color operations. The adaptation of the LCD's using the color filters for all-color displays is attained by the method for displaying mixed colors by utilizing the integrating effect of human eyes due to addition color mixture (direct vision type color LCS), the method for displaying lights of three primary colors as actually overlapped (projection), etc. As respects the array of picture elements in the color filters, the stripe array which is adopted for OA devices required to display sharply such still images as graphics and characters or the mosaic array or the triangle array which is adopted for time-varying images requiring clear high-resolution displays has been selected.
Generally, these color filters are basically constructed by superposing, on a substrate such as of glass or plastic image pickup element or a thin-film transistor, a black matrix and a color pattern having minute colored picture elements laid out in a pattern with colored layers of red, green, and blue (RGB), superposing a transparent overcoat layer on the colored pattern, and further superposing thereon a transparent conductive film. The methods for the production of color filters provided with a color pattern having RGB colored picture elements laid out in a pattern are broadly classified under dyeing methods using dyes as the components for the colored layers and pigment methods using pigments as the components.
At present, the color filters based on colored layers using pigments are predominant because they excel in thermal resistance, chemical resistance, and lightfastness. As one of the typical methods for the production of color filters based on colored layers using pigments, the photosensitive resin based dye dispersion method which comprises applying to a substrate a photosensitive resin coloring composition having a pigment dispersed therein (pigment resist) thereby forming a colored layer and patterning the colored layer by the photolithographic technique thereby forming the color pattern has been known. The pigment dispersion method is known in two types, i.e. the polymerization type using acrylic resin as the base material for the colored layer and the cross-linking type using a polyvinyl alcohol compound. Specifically, the pigment dispersion method comprises dispersing a pigment in the base material and manufacturing the resultant dispersion into a resist by using such a sensitive material as azide or bisazide in the cross-linking type or by adding a photocurable monomer and such a photopolymerization initiator as benzophenone, Irgacure, or triazine in the polymer type.
FIG. 1 is a schematic diagram illustrating the production process of the photosensitive resin based pigment dispersion method. As illustrated in FIG. 1, a black matrix 3 is first formed on a glass substrate 1 [Step (1) shown in FIG. 1A]. A pigment resist formed by dispersing a pigment (photosensitive resin coloring composition) is then spread on the glass substrate 1 to form a colored layer 5 [Step (2) shown in FIG. 1B]. Subsequently, an oxygen-repelling film 7, for example, is formed on the colored layer 5 in the polymer type [Step (3) shown in FIG. 1C]. As a result, the layers so far produced can be exposed to light in an inert condition at the next step (4). The layers are then exposed to light through the medium of a photomask 9 of a negative pattern [Step (4) shown in FIG. 1D]. The exposed colored layer is developed with an alkali to obtain a color pattern 11 [Step (5) shown in FIG. 1E]. The steps (2)-(5) are repeated three times to form color patterns 11, 13 and 15 having colored picture elements of RGB laid out in a pattern [Step (6) shown in FIG. 1F]. Thereafter, a transparent overcoat layer 17 is formed to protect the color patterns 11, 13 and 15 and smooth the surface (by further formation of a transparent conductive film) and complete a color filter [Step (7) shown in FIG. 1G].
Since the photosensitive resin based pigment dispersion method allows no sufficient dispersion of the pigment in the resin as compared with the method using a dye, the color filter obtained thereby has such problems as offering no sufficient transmittance, manifesting a prominent action of disturbing polarized light, and impairing the contrast of the panel. The polymerization type necessitates superposition of an oxygen-repelling film for the purpose of preventing the degradation of sensitivity due to the influence of oxygen during the course of exposure and, therefore, has the problem of complicating the process.
The etching type pigment dispersion method which has been recently developed is admitted to enjoy a generous improvement in quality in terms of resistance because it uses in the base resin thereof polyimide which possesses high thermal resistance as a resin coloring composition. Since this base resin has no photosensitivity, it necessitates a resist. In addition to the problems mentioned above, this method incurs the problem of increasing the number of steps of process.
The printing method which uses an ink obtained by dispersing a pigment in an epoxy resin, the electrodeposition method which forms a colored layer with an electrodeposition grade electrode by the use of a resin coloring composition having a pigment dispersed in an acrylic resin or an epoxy resin, the transfer method which comprises the steps of forming films of three colors of RGB by the application of a resist resin (photosensitive resin coloring composition) having a pigment dispersed in a resin, pasting the films severally to a glass substrate, and peeling the films thereby completing a color filter, and the method which selectively colors a polysilane film by the sol-gel technique using having a pigment dispersed in silica have been also know. The pigment methods of all the types, however, invariably have the same problems as the photosensitive resin based pigment dispersion method mentioned above. The electrodeposition method, though allowed to use an electrodeposition grade electrode (pattern electrode) as a display grade electrode, requires to form a transparent electrode of low resistance after the formation of a protective film layer and entails the problem of lowering the transmittance because the use of the electrodeposition grade electrode results in degrading the effect of display. The printing method, notwithstanding the printing itself is easy, is further at a disadvantage in being conspicuously inferior to the photolithography method in surface accuracy, dimensional accuracy, and surface smoothness of the produced color pattern.
As a means to produce the color filter with a colored layer using a dye (dyeing method), the relief dye method which comprises a patterning step by the photolithographic technique using a dyeable resin and a dyeing step has been well known. This dyeing method does not use a resin coloring composition but effects dyeing a transparent resin pattern in the course of the process of production.
FIG. 2 is a schematic diagram illustrating a process of production of the dyeing method. First, a black matrix 203 is formed on a glass substrate 201 as shown in FIG. 2 [Step (1) shown in FIG. 2A]. Then, a transparent resist to be dyed (a water-soluble polymeric compound such as dyeable gelatin or casein endowed with photosensitivity by addition of a bichromate) is applied to the glass substrate 201 and the applied layer of the transparent resist 205 is dried [Step (2) shown in FIG. 2B]. The resist is exposed to an ultraviolet light passed through a photomask 207 of a negative pattern 208 [Step (3) shown in FIG. 2C]. The exposed resist is developed with water to obtain a relief pattern 208 [Step (4) shown in FIG. 2D]. Then, the relief pattern 208 is adjusted by heating to a proper hardness and dyed with an acid dye or a reactive dye [Step (5) shown in FIG. 2E]. Further, for the purpose of preventing mixture of colors, the dyed pattern is given a dye-resisting (fixing) treatment as with tannic acid or a treatment for the insertion of an intermediate layer 212 with thermosetting urethane resin or acrylic resin to produce color patterns 211, 213 and 215 [Step (6) shown in FIG. 2F]. The steps (2)-(6) are repeated three times to form color patterns 211, 213 and 215 having colored picture elements of RGB laid out in a pattern [Step (7) shown in FIG. 2G]. Thereafter, a transparent overcoat layer is formed to protect the color patterns 211, 213 and 215 and smooth the surface (by further formation of a transparent conductive film) and complete a color filter [Step (8) shown in FIG. 2H].
As another form of the dyeing method, the dye dispersion method which forms a color pattern by applying a colored polyimide having a dye dispersed in polyimide (resin coloring composition) to a substrate thereby forming a cored layer, superposing a layer of resist on the colored layer, and patterning the layer of resist by the photolithographic technique has been known.
FIG. 3 is a schematic diagram illustrating a process of production of the dye dispersion method. First, a black matrix 303 is formed on a glass substrate 301 as shown in FIG. 3 [Step (1) shown in FIG. 3A]. Then, a colored polyimide having a dye dispersed therein (resin coloring composition) is applied to a glass substrate 301 and the applied layer of polyimide is dried to form a colored layer 305 (colored polyimide layer) [Step (2) shown in FIG. 3B]. A positive resist is superposed on the colored layer 305 [Step (3) shown in FIG. 3C]. Then, the positive resist is exposed to light through a photomask 309 [Step (4) shown in FIG. 3D]. The exposed positive resist 306 is subsequently developed with an aqueous alkali solution [Step (5) shown in FIG. 3E]. The colored layer 305 is etched and the positive resist 306 is peeled [Step (6) shown in FIG. 3E]. Further, for the purpose of preventing mixture of colors, the dyed pattern is given a treatment for the insertion of an intermediate layer 312 with thermosetting urethane resin or acrylic resin to produce a color pattern [Step (7) shown in FIG. 3G]. The steps (2)14 (7) are repeated three times to form color patterns 311, 313 and 315 having colored picture elements of RGB laid out in a pattern [Step (8) shown in FIG. 3H]. Thereafter, a transparent overcoat layer 317 is formed to protect the color patterns 311, 313 ad 315 and smooth the surface (by further formation of a transparent conductive film) and complete a color filter [Step (9) shown in FIG. 3I].
The color filter produced by the dyeing method mentioned above enjoys superiority to the pigment method mentioned above in terms of coloration, suffers inferiority to the pigment method in terms of thermal resistance, durability, and chemical resistance of the dye used in the coloring material, and requires essentially the antifouling treatment for prevention of mixture of colors and the formation of an intermediate layer because the dyes induce color smear (color migration) in the course of spin coating. Further, the dye dispersion method has the patterned polyimide in an at least semi-cured state and, therefore, incurs difficulty in having the dye diffused in the polyimide. Since it uses the polyimide as the base resin, it enjoys a marked improvement in the quality of resistance. Since it is devoid of photosensitivity, it necessitates formation of a resist layer and consequently entails the problem of increasing the number of steps of process. Further, the dyeing method essentially needs to incorporate in the process thereof a step of dyeing which demands a complicated control and, therefore, inevitably adds to the number of steps of process and poses the problem of rendering the process complicated. It is for the purpose of preventing mixture of colors due to infliction of an injury that the dyeing method utilizes the antifouling treatment intended to preclude color mixture and the formation of an intermediate layer. When the pattern of the n+1'th color is formed without coating the pattern of the n'th color (n=1, 2) with an intermediate protective layer, for example, the pattern of the n'th color, after the coating liquid (resin coloring composition) of the n+1'th color has been applied thereto, sustains a crack therein or gathers wrinkles thereon, releases the dye therefrom, or dissolves and flows out itself and, because of the ensuing injuries, induces mixture of colors. The antifouling treatment or the treatment for the formation of an intermediate layer is carried out for the purpose of precluding the mixture of colors due to such injuries as mentioned above.
Particularly, for the solution of the various problems mentioned above, improvements brought about in various physical properties of the photosensitive resin coloring compositions for use in the color filters owing to the development of novel dyes and improvements achieved in manufacturing methods owing to the simplification of process steps have been proposed.
From the viewpoint of improving various physical properties of photosensitive resin coloring compositions for use in color filters owing to the development of novel dyes thereby obtaining dye materials retaining the color inherent in the conventional dye type and manifesting high durability and producing color filters using the dye materials, phthalocyanine compounds containing a substituent have been developed as dye materials possessing high durability and manifesting solubility in a solvent. Examples of using such soluble phthalocyanine compounds in color filters have been proposed in JP-A-01-233,401 and JP-A-05-295,283.
The phthalocyanine compounds containing a substituent at the .beta. position which are disclosed in JP-A-01-233,401 are excellent in durability and nevertheless are dificient in properties of transmittance.
The phthalocyanine compounds containing a substituent having a hetero atom at the .alpha. position are proposed in JP-A-05-295,283 as compounds capable of overcoming such drawbacks as mentioned above to a fair extent. Notwithstanding these compounds have been proposed as dyes for use in green color filters, they require to contain therein a yellow-dye in such a large amount as the neighborhood of 50% of the total amount of dyes for the purpose of acquiring properties of transmittance fit for a dye for a green color filter. Thus, they are deficient in properties of transmittance. These phthalocyanine compounds are not necessarily fully satisfactory in all the properties and, therefore, are preferred to possess still better properties.
As examples of using anthraquinone compounds and quinizarine compounds as dyes for color filters, JP-A-62-197459, JP-A-63-135,454, JP-A-63-139,948, JP-A-63-223,064, JP-A-63-221,170, JP-A-63-235,371, JP-A-63-235,371, JP-A-05-25,599, etc. disclose blue dyes for filters, JP-A-62-235,366, JP-63-268,768, etc. disclose green dyes for filters, and JP-05-5,067, etc. disclose red dyes for filters.
The anthraquinone compounds and quinizarine compounds cited above do not fulfill solubility, durability, thermal resistance, and properties of transmittance wholly.
The present inventors have proposed in JP-A-07-267,559, JP-A-08-50,260, and JP-A-08-70,627 dyes manifesting excellent solubility in resins and color filters manufactured therefrom.
The inventions proposed in these patent publications are capable of solving the problems mentioned above. Today, the color filter grade photosensitive resin coloring compositions and the color filters manufactured therefrom are demanded to offer higher qualities. To satisfy these requirements and particularly color tone, it is preferred to create three primary color RGB pigments and dyes which occupy the largest permissible triangle in the triangle of the existent colors on the chromaticity diagram and a color filter manufactured therewith. In this respect, the inventions proposed as described above are not perfectly satisfactory.
From the viewpoint of overcoming the drawbacks mentioned above by improving the process of manufacture of a color filter as by simplifying the steps of production and consequently producing a color filter retaining the color inherent in the conventional dye and manifesting high durability, JP-B-07-82,124, for example, proposes a dye dispersion method which forms a color pattern by applying a polyimide precursor solution containing a dye to a substrate thereby forming a colored layer, superposing a resist on the colored layer, and patterning the superposed resist layer by the photolithographic technique.
The dye dispersion method which is disclosed in the patent publication requires to perform the same steps (1)-(6) as in the dye dispersion method described above with reference to FIG. 3. Then, the color layers, without preparatorily forming thereon an intermediate layer for the prevention of mixture of colors, are hardened at an elevated temperature to obtain a firm color pattern [Step (7)]. The steps (2)-(7) are repeated three times to form a color pattern having colored picture elements of RGB laid out in a pattern [Step (8)]. Thereafter, a transparent overcoat layer is formed to protect the color pattern and smooth the surface (by further formation of a transparent conductive film) and complete a color filter [Step (9)].
The dye dispersion method which is disclosed in the patent publication mentioned above has the advantage of obviating the necessity for forming an intermediate layer intended to preclude mixture of colors. Since it uses the polyimide precursor solution, it necessitates formation of a resist layer on account of the absence of photosensitivity and confronts an unsolved technical problem of inevitable addition to the number of steps of process.